Angiogenesis is required for the growth and metastasis of solid tumors. The anti-malarial agent dihydroartemisinin (DHA) demonstrates potent anti-angiogenic activity, but the underlying molecular mechanisms are not yet fully understood. During the process of angiogenesis, endothelial cells migrating from existing capillaries may undergo programmed cell death after detaching from the extracellular matrix, a process that is defined as anchorage-dependent apoptosis or anoikis. In the present study, DHA-induced cell death was compared in human umbilical vein endothelial cells (HUVECs) cultured in suspension and attached to culture plates. In suspended HUVECs, the cell viability was decreased and apoptosis was increased with the treatment of 50 &micro;M DHA for 5 h, while the same treatment did not affect the attached HUVECs. In addition, 50 &micro;M DHA increased the phosphorylation of c-Jun N-terminal kinase (JNK) in suspended HUVECs, but not in attached HUVECs, for up to 5 h of treatment. The JNK inhibitor, SP600125, reversed DHA-induced cell death in suspended HUVECs, suggesting that the JNK pathway may mediate DHA-induced endothelial cell anoikis. The data from the present study indicates a novel mechanism for understanding the anti-angiogenic effects of DHA, which may be used as a component for chemotherapy.

Mentions:
The effects of DHA on the cell viability of HUVECs were evaluated by trypan blue exclusion assay. After 5 h in suspension, the cell viability of HUVECs in the non-treatment group was significantly decreased compared with the attached HUVECs (88.3±4.6% vs. 73.6±3.1%; P=0.03). The percentage of viable cells in attached HUVECs was not affected by 50 µM DHA after 5 h incubation (88.3±4.6% vs. 90.7±6.1%; P=0.23) (Fig. 1A). However, the percentage of viable cells in suspended HUVECs was significantly decreased after the same DHA treatment (73.6±3.1% vs. 58.7±8.1%; P=0.02) (Fig. 1B). Therefore, DHA is likely to inhibit the cell viability of suspended endothelial cells but not attached endothelial cells.

Mentions:
The effects of DHA on the cell viability of HUVECs were evaluated by trypan blue exclusion assay. After 5 h in suspension, the cell viability of HUVECs in the non-treatment group was significantly decreased compared with the attached HUVECs (88.3±4.6% vs. 73.6±3.1%; P=0.03). The percentage of viable cells in attached HUVECs was not affected by 50 µM DHA after 5 h incubation (88.3±4.6% vs. 90.7±6.1%; P=0.23) (Fig. 1A). However, the percentage of viable cells in suspended HUVECs was significantly decreased after the same DHA treatment (73.6±3.1% vs. 58.7±8.1%; P=0.02) (Fig. 1B). Therefore, DHA is likely to inhibit the cell viability of suspended endothelial cells but not attached endothelial cells.

Angiogenesis is required for the growth and metastasis of solid tumors. The anti-malarial agent dihydroartemisinin (DHA) demonstrates potent anti-angiogenic activity, but the underlying molecular mechanisms are not yet fully understood. During the process of angiogenesis, endothelial cells migrating from existing capillaries may undergo programmed cell death after detaching from the extracellular matrix, a process that is defined as anchorage-dependent apoptosis or anoikis. In the present study, DHA-induced cell death was compared in human umbilical vein endothelial cells (HUVECs) cultured in suspension and attached to culture plates. In suspended HUVECs, the cell viability was decreased and apoptosis was increased with the treatment of 50 &micro;M DHA for 5 h, while the same treatment did not affect the attached HUVECs. In addition, 50 &micro;M DHA increased the phosphorylation of c-Jun N-terminal kinase (JNK) in suspended HUVECs, but not in attached HUVECs, for up to 5 h of treatment. The JNK inhibitor, SP600125, reversed DHA-induced cell death in suspended HUVECs, suggesting that the JNK pathway may mediate DHA-induced endothelial cell anoikis. The data from the present study indicates a novel mechanism for understanding the anti-angiogenic effects of DHA, which may be used as a component for chemotherapy.